Recent advances in microelectronics have included the use of high-k films in gate dielectric stacks for logic applications. To increase device reliability and reduce electron leakage from the gate electrode to the transistor channel, semiconductor transistor technology is introducing high-k materials that allow increased physical thickness of the gate dielectric layer. Dielectric materials featuring a dielectric constant greater than that of SiO2 (k˜3.9) are commonly referred to as high-k materials. An early motivation for seeking high-k films for use in metal-oxide field effect transistors (MOSFETs) was one of simply reducing the leakage current without reducing the film capacitance. Furthermore, for many applications, the high-k films need to have the electrical equivalent of a SiO2 layer having a physical thickness, Tox, of about 1 nm.
Nitrogen incorporation into high-k films has been shown to improve many of the film properties for semiconductor devices, including increasing crystallization temperature, increasing the k value, and improving the barrier properties of the high-k films. However, incorporating nitrogen into the high-k films has turned out to be difficult and often requires the use of nitrogen-containing plasma that contain high energy charged species that can damage materials in the semiconductor device.